Approximately 20% of adults suffer from allergy to cats and/or their dander. Symptoms of cat allergies range from mild rhinitis and conjunctivitis to life-threatening asthmatic responses, and cat allergies are a major roadblock to cat ownership. For example, cat allergy is the primary reason given by cat owners for returning cats to animal shelters.
Most cat allergies are caused by a small stable glycoprotein called Fel D1 (Feline domesticus allergen number 1). This protein is transferred to cat dander by their grooming process and becomes airborne. Upon inhalation of cat dander having Fel D1 attached, an allergy cascade is triggered because of the recognition of the Fel D1 by human immune cells.